Re: [PATCH 01/28] drm: Polish fbdev helper struct docs

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Dec 07, 2015 at 11:45:22AM +0100, Thierry Reding wrote:
> On Fri, Dec 04, 2015 at 09:45:42AM +0100, Daniel Vetter wrote:
> > Mostly this is just adding extensive docs for the callbacks, but also
> > a few other additions.
> > 
> > v2: Use FIXME comments to annotate helper hooks that should be
> > replaced.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > ---
> >  include/drm/drm_fb_helper.h | 92 ++++++++++++++++++++++++++++++++++++++-------
> >  1 file changed, 79 insertions(+), 13 deletions(-)
> > 
> > diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> > index 87b090c4b730..5ce033e36039 100644
> > --- a/include/drm/drm_fb_helper.h
> > +++ b/include/drm/drm_fb_helper.h
> > @@ -74,25 +74,76 @@ struct drm_fb_helper_surface_size {
> >  
> >  /**
> >   * struct drm_fb_helper_funcs - driver callbacks for the fbdev emulation library
> > - * @gamma_set: Set the given gamma lut register on the given crtc.
> > - * @gamma_get: Read the given gamma lut register on the given crtc, used to
> > - *             save the current lut when force-restoring the fbdev for e.g.
> > - *             kdbg.
> > - * @fb_probe: Driver callback to allocate and initialize the fbdev info
> > - *            structure. Furthermore it also needs to allocate the drm
> > - *            framebuffer used to back the fbdev.
> > - * @initial_config: Setup an initial fbdev display configuration
> >   *
> >   * Driver callbacks used by the fbdev emulation helper library.
> >   */
> >  struct drm_fb_helper_funcs {
> > +	/**
> > +	 * @gamma_set:
> > +	 *
> > +	 * Set the given gamma lut register on the given crtc.
> > +	 *
> > +	 * This callback is optional.
> > +	 *
> > +	 * FIXME:
> > +	 *
> > +	 * This callback is functionally redundant with the core gamma table
> > +	 * support and simply exists because the fbdev hasn't yet been
> > +	 * refactored to use the core gamma table interfaces.
> > +	 */
> >  	void (*gamma_set)(struct drm_crtc *crtc, u16 red, u16 green,
> >  			  u16 blue, int regno);
> 
> Pardon my ignorance, but is there a way to document parameters with this
> new syntax?

Unfortunately not. Doing that would be quite a bit more rework of the
entire kerneldoc toolchain I think.
> 
> > +	/**
> > +	 * @gamma_get:
> > +	 *
> > +	 * Read the given gamma lut register on the given crtc, used to save the
> > +	 * current lut when force-restoring the fbdev for e.g. kdbg.
> > +	 *
> > +	 * This callback is optional.
> > +	 *
> > +	 * FIXME:
> > +	 *
> > +	 * This callback is functionally redundant with the core gamma table
> > +	 * support and simply exists because the fbdev hasn't yet been
> > +	 * refactored to use the core gamma table interfaces.
> > +	 */
> >  	void (*gamma_get)(struct drm_crtc *crtc, u16 *red, u16 *green,
> >  			  u16 *blue, int regno);
> 
> Nit: While at it, perhaps (here and in the @gamma_set documentation):
> s/lut/LUT/ and s/crtc/CRTC/?

Yeah I thought about our inconsistency wrt upper-case of abbrevations in
the docs. I think we should do this as a trivial patch thing for newbies.

> > +	/**
> > +	 * @fb_probe:
> > +	 *
> > +	 * Driver callback to allocate and initialize the fbdev info structure.
> > +	 * Furthermore it also needs to allocate the drm framebuffer used to
> > +	 * back the fbdev.
> > +	 *
> > +	 * This callback is mandatory.
> > +	 *
> > +	 * RETURNS:
> > +	 *
> > +	 * The driver should return 0 on success and a negative error code on
> > +	 * failure.
> > +	 */
> >  	int (*fb_probe)(struct drm_fb_helper *helper,
> >  			struct drm_fb_helper_surface_size *sizes);
> 
> Nit: s/drm/DRM/
> 
> >  /**
> > - * struct drm_fb_helper - helper to emulate fbdev on top of kms
> > + * struct drm_fb_helper - main structure to emulate fbdev on top of kms
> 
> s/kms/KMS
> 
> >   * @fb:  Scanout framebuffer object
> >   * @dev:  DRM device
> 
> There seems to be an extra space between the : and the description. That
> was already there, but maybe worth a follow-up.

I think fix that up while applying, same for the others.
-Daniel

> 
> >   * @crtc_count: number of possible CRTCs
> >   * @crtc_info: per-CRTC helper state (mode, x/y offset, etc)
> >   * @connector_count: number of connected connectors
> >   * @connector_info_alloc_count: size of connector_info
> > + * @connector_info: array of per-connector information
> >   * @funcs: driver callbacks for fb helper
> >   * @fbdev: emulated fbdev device info struct
> >   * @pseudo_palette: fake palette of 16 colors
> > - * @kernel_fb_list: list_head in kernel_fb_helper_list
> > - * @delayed_hotplug: was there a hotplug while kms master active?
> > + *
> > + * This is the main structure used by the fbdev helpers. Drivers supporting
> > + * fbdev emulation should embedded this into their overall driver structure.
> > + * Drivers must also fill out a struct &drm_fb_helper_funcs with a few
> > + * operations.
> >   */
> >  struct drm_fb_helper {
> >  	struct drm_framebuffer *fb;
> > @@ -129,10 +184,21 @@ struct drm_fb_helper {
> >  	const struct drm_fb_helper_funcs *funcs;
> >  	struct fb_info *fbdev;
> >  	u32 pseudo_palette[17];
> > +
> > +	/**
> > +	 * @kernel_fb_list:
> > +	 *
> > +	 * Entry on the global kernel_fb_helper_list, used for kgdb entry/exit.
> > +	 */
> >  	struct list_head kernel_fb_list;
> >  
> > -	/* we got a hotplug but fbdev wasn't running the console
> > -	   delay until next set_par */
> > +	/**
> > +	 * @delayed_hotplug:
> > +	 *
> > +	 * A hotplug was received while fbdev wasn't in control of the drm
> > +	 * device, i.e. another kms master was active. The output configuration
> > +	 * needs to be reprobe when fbdev is in control again.
> 
> s/drm/DRM/, s/kms/KMS/
> 
> Otherwise looks really good.
> 
> Thierry



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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